This section provides background information related to the present disclosure which is not necessarily prior art.
In the tobacco industry, one of the key processes of tobacco production is leaf curing. Among many types of curing barns are two main types. One type uses coal as a heat source while the other type uses a heat pump as a heat source. Coal-fueled tobacco curing can generate huge amounts of pollution, which is why heat pumps are regarded as an alternative heat source for tobacco leaf processing.
Although a heat pump used for a curing barn emits essentially zero pollution, the price of heating is a concern. For a typical load of 3500 kilograms of fresh tobacco leaves, the energy consumed to dry the leaves is around 750 kilowatt hours.
Another issue with heat pump curing is the typical control system for the heat pump. Because coal-fueled tobacco curing barns presently have the largest market share, the typical control system for heat pump curing has been developed based on the characteristics of the control systems for coal-fueled tobacco curing barns.
There are very few control systems dedicated for a heat pump curing barn, as most control systems for heat pump curing bars are modified from coal-fueled curing control systems. Heat pump curing controls generally are only modifications of existing coal curing controls. For example, a typical heat pump controller switches compressors on and off by means of a single line commonly used by a controller in a coal burning system to control the operation of a blower.